Danian/Selandian boundary criteria and North Sea Basin ... based on calcareous nannofossil and foraminiferal trends in SW France Etienne Steurbaut a,!, ... implies contemporaneity

Author's personal copy

Danian/Selandian boundary criteria and North Sea Basin–Tethys

correlations based on calcareous nannofossil and

foraminiferal trends in SW France

Etienne Steurbaut a,⁎, Károly Sztrákos b

a Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussel and KULeuven, Belgiumb Hall A3, 35, rue Savier, 92240 Malakoff, France

Received 30 April 2007; received in revised form 22 August 2007; accepted 23 August 2007

Abstract

High-resolution calcareous nannofossil and foraminiferal investigations of the Bidart and Loubieng outcrop sections allow to

define a time-calibrated sequence of 47 bio-events within the Danian/Selandian (D/S) boundary interval (61.2–59.7 Ma) of

Aquitaine (SW France). The D/S boundary, as originally defined in Denmark (start of clastic sedimentation at the base of the

Lellinge Greensand Formation), is marked by the end of the acme of the nannofossil family braarudosphaeraceae. This bio-event,

dated at 59.9 Ma, has also been identified at the lithological change from limestone-dominated (Lasseube Formation) to marly

sedimentation (Latapy Member of the Pont-Labau Formation) in SW Aquitaine and at the base of the red marls of the Itzurun

Formation at Zumaia (Spain), recently designated as Global Stratotype Section and Point (GSSP) for the D/S boundary. This

implies contemporaneity of this lithological shift throughout Europe and a GSSP proposal, which is consistent with the original

boundary definition. The braarudusphaeraceae-event is believed to be due to the interruption of freshwater influx, probably related

to a sudden decrease in precipitation. It is located at the top of nannofossil zone NP4 and within planktonic foraminiferal zone P3b

and bracketed between the lowest occurrence (LO) of Morozovella velascoensis (below) and the LO of Fasciculithus

tympaniformis (above). It is coincident with the LO of Bomolithus elegans, the LCsO (Cs = consistent) of Fasciculithus janii and

the LO of Subbotina velascoensis. The D/S boundary as originally defined is 400 k.y. posterior to a major discontinuity, recorded

throughout the Tethyan Realm (Tunisia, Egypt) and up to now erroneously considered to correspond to the D/S boundary. This

break in sedimentation, dated at 60.3 Ma and coinciding with the P3a/P3b boundary, is due to a major sea-level fall. It is correlated

with sedimentation changes in the Aquitaine–Zumaia area (start of development of marly interbeds) and in the North Sea Basin

(transition Bryozoan limestone–Calcisiltite in Denmark; transition shallow marine Mons Formation–continental Hainin Formation

in Belgium). The Loubieng section supplements the Zumaia section. Because of its rich and well-preserved fossil content and

continuous sedimentation it constitutes an excellent auxiliary section for the D/S boundary.

© 2007 Elsevier B.V. All rights reserved.

Keywords: Danian/Selandian boundary; calcareous nannofossils; foraminifera; France; North Sea Basin–Tethys correlations

Available online at www.sciencedirect.com

Marine Micropaleontology 67 (2008) 1–29www.elsevier.com/locate/marmicro

⁎ Corresponding author. Fax: +32 2 627 41 13.

E-mail addresses: [email protected] (E. Steurbaut), [email protected] (K. Sztrákos).

0377-8398/$ - see front matter © 2007 Elsevier B.V. All rights reserved.

doi:10.1016/j.marmicro.2007.08.004


1. Introduction

The Danian/Selandian (D/S) transition is supposed to

correspond to the first out of six short episodes of

extreme warming, called hyperthermals, which occurred

in the early Paleogene (Thomas and Zachos, 2000).

They are superimposed on a long-term global warming

trend, extending from the Mid-Paleocene into the Early

Eocene (Zachos et al., 2001). The causes and biotic

consequences of the Mid-Paleocene Hyperthermal

(MPH) are currently under study. Major faunal changes

have been recorded within the D/S boundary interval in

the North Sea Basin (Clemmensen and Thomsen, 2005)

and in the Tethyan Realm (Egypt: Speijer, 2003;

Tunisia: Steurbaut et al., 2000; Guasti et al., 2005,

2006; Van Itterbeeck et al., 2007), but their exact

relations and timing are uncertain through lack of a

high-resolution integrated stratigraphic framework.

The abrupt shift from carbonate to siliciclastic

sedimentation marking the D/S boundary in Denmark

(Thomsen and Heilmann-Clausen, 1985; Thomsen,

1994) and Belgium (Steurbaut, 1998) has been linked

to the uplift of the Scotland-Shetland Platform, initiating

a massive input of siliciclastic sediments in the North

Sea Basin (Clemmensen and Thomsen, 2005). In

Denmark, the type region of the Danian and Selandian

Stages, this lithological shift seems to coincide with

major biotic changes, including a decline in the

abundance of the nannofossil taxon Braarudosphaera,

an increase in percentage of planktonic foraminifera and

substantial quantitative changes in benthic foraminifera

(Clemmensen and Thomsen, 2005) and dinoflagellate

cysts (Heilmann-Clausen, 1985, 1994; Stouge et al.,

2000). Although these bio-events offer good opportu-

nities for interregional correlation, estimation of the age

of the lithofacies shift through magnetobiochronologic

calibration remains problematic. The standard Late

Danian and Early Selandian planktonic foraminiferal

and calcareous nannofossil zones, through which the

age estimation is calibrated, cannot be identified in the

North Sea Basin, because of paucity or absence of the

relevant index species.

A similar lithological shift from carbonates to marls

has been recorded in the Zumaia section in northern

Spain (Fig. 1). This lithological change, characterised by

red marl-limestone couplets abruptly passing upwards

Fig. 1. Location of the Danian/Selandian boundary sections discussed here, superimposed on the paleogeographic situation in Europe and northern

Africa around the Maastrichtian–Paleocene transition (modified after Gheerbrandt and Rage, 2006). Tunisia (A) and Egypt (B) are shown in more

detail.

2 E. Steurbaut, K. Sztrákos / Marine Micropaleontology 67 (2008) 1–29


into 3.4 m thick red marl, is one of the most prominent at

Zumaia (Schmitz et al., 1998). It is located in the upper

part of nannofossil zone NP 4 (75 cm below the lowest

occurrence of Fasciculithus tympaniformis, defining the

base of NP5) and marked by a sharp decrease in

Braarudosphaera bigelowii, a nannofossil taxon known

to bloom in coastal hyposaline conditions (Bukry,

1974). The drastic decrease in Braarudosphaera at the

base of the red marl (boundary between the Danian

Limestone Formation and the Itzurun Formation

according to Baceta et al., 2006) has been upheld in a

current nannofossil study by Bernaola and Nuño-Arana

(2006). The LO of F. tympaniformis, however, was

relocated at about 2.5 m above the lithological

boundary.

Analogous reddish marl-limestone successions have

been mentioned from the southwestern part of the

Aquitaine Basin, e.g. at Bidart and Loubieng (Pey-

bernès et al., 2000; Sztrákos, 2005b; Sztrákos and

Steurbaut, 2007) (Fig. 2). The Loubieng quarry, located

300 m east of the crossing of road N 647 Orthez-

Navarrenx with road D 110 Loubieng-Sauvelade

exposes the most complete Danian/Selandian boundary

section of Aquitaine, but was not studied in much detail

up to now. Sztrákos and Steurbaut (2007) recently

reviewed its stratigraphy and discussed previous

investigations, which often seemed to have led to

erroneous interpretations. The higher parts of the

Selandian are continuously exposed in the Gan-

Rébénacq road section, 60 km southeast of Loubieng

(Steurbaut and Sztrákos, 2002).

Further southward into the Tethys area sedimentation

conditions are completely different (Fig. 1). During most

of the Danian and Selandian, from c 63 Ma to 58.5 Ma,

monotonous sequences developed on the northwestern

margin of the Arabian-Nubian shield in Egypt (Said,

1962), as well as in the Tunisian trough in the western part

of the southern Tethys (Steurbaut et al., 2000). Abrupt

sedimentation shifts occurred simultaneously in both

areas, marked by omission surfaces overlain by special

lithologies: a purplish brownmarl bed, laminated and rich

in fish debris within the hemipelagic Dakhla Formation in

Egypt (Sprong et al., in press) and complex channel

systems with glauconite infill within the marly El Haria

Formation in Tunisia (Steurbaut et al., 2000). The latter,

believed to coincide with the P2/P3a planktonic forami-

niferal zonal boundary (lowest occurrence of Morozo-

vella angulata, according to Molina in Steurbaut et al.,

2000) and fallingwithin nannofossil zoneNP4 (Steurbaut

et al., 2000), was equated with the D/S boundary,

following the interpretation of Berggren et al. (1995).

However, in recent investigations (Guasti et al., 2006;

Van Itterbeeck et al., 2007; Sprong et al., in press) it

was suggested that the lithological break correspond to

the P3a/P3b boundary, using the lowest occurrence of

slightly keeled Igorina as zonal boundary criterion.

Fig. 2. Map with the location of the Bidart and the Loubieng outcrop sections in SWAquitaine (France).

3E. Steurbaut, K. Sztrákos / Marine Micropaleontology 67 (2008) 1–29


Despite the recent release of numerous new microfossil

data (essentially ostracods and benthic foraminifera), the

relation of this major event with the D/S boundary in the

type area remains unclear.

Here, we aim at clarifying existing Late Danian and

Early Selandian correlation problems between the North

Sea Basin and the Tethys through the study of the

Loubieng and Bidart outcrops in the Aquitaine Basin,

integrating lithology, foraminifera and calcareous nan-

nofossil records. The data from the North Sea Basin are

based on Varol (1989), Steurbaut (1998) and Clem-

mensen and Thomsen (2005), the Tethys data are from

Tunisian (Steurbaut et al., 2000; Guasti et al., 2005;

2006; Van Itterbeeck et al., 2007) and Egyptian sections

(Speijer, 2003; Sprong et al., in press).

2. The Bidart and Loubieng sections: geological

setting and lithostratigraphy

The Bidart section, a 60 m long and several tens of m

high cliff south of Biarritz in the extreme SW of

Aquitaine (Fig. 2, IGN map Bayonne-Biarritz, 1244E;

x∼282.650, y∼3125.400), includes a series of essen-

tially whitish and pink limestones from late Cretaceous

to Late Danian age. The succession, the lower part of

which is interrupted by faults or slumping structures, has

been documented by Sztrákos and Steurbaut (2007).

The topmost 15 m, consisting of undisturbed limestones

with several tiny marl beds and belonging to the

Lasseube Formation, is re-discussed here (Fig. 3).

The Loubieng quarry is located in the North-Pyrenean

Tectonic Zone (43° 25′ 37.19″ N, 0° 44′ 41.04″ W; IGN

map Orthez, 1444E; x=350.400, y=3129.900), which

westwards of Pau is fractured into several tectonic units. It

sits on the northern limb of a syncline, the centre of which

covers the Sauvelade village, and belongs to the Sauvelade

tectonic unit (Rocher et al., 2000; Serrano et al., 2001;

Sztrákos et al., 2003). The Loubieng section consists of

several faulted blocks marked by small displacements

(throw of a few meters) along normal faults (Rocher et al.,

2000, Fig. 6G). The lower part of the section belongs to the

upper part of the Lasseube Limestone or Lasseube

Formation (Sztrákos et al., 1997; Sztrákos and Steurbaut,

2007) (Fig. 4). It forms the quarry front and consists of an

alternation of limestone beds (20 to 40 cm thick) and tiny

marl intercalations. The marls with tiny sand and

calcarenite intercalations, overlying the quarry front are

included in the Latapy Member, which in Western

Aquitaine represents the lowermost unit of the Pont-

Labau Formation (Sztrákos, 2005b).

The rhythmicity within the Lasseube Formation

is fairly constant, despite some thickness differences. It

is disrupted at six levels, marked by special lithologies,

labelled in ascending order A to F. These marker beds

are excellent reference levels, which can easily be

followed throughout the quarry (Figs. 4 and 5). Marker

bedA, at the base of the quarry, consists of a 1 to 2m thick

calcareous conglomerate. Beds B and C are bioclastic

calcareous grainstones, with a thickness of about 0.6 m. D

includes a series of folded limestones (∼1.5 m), due to

slumping, whereas E is a massive conglomeratic and

bioclastic limestone (∼0.8 m). F (∼0.2 m) is the highest

Fig. 3. The Bidart outcrop section, with location of the major

stratigraphic units, details of the lithological succession and location of

samples.



limestone bed recorded, overlying 0.25 m of reddish marl

(Fig. 6). It is overlain by the Latapy Member, including

grey highly bioturbated clays, which up-section pass into

homogenous grey bioturbated marls.

3. Materials and methods

The Loubieng quarry was logged and sampled in

September 2002 by K. Sztrákos (details in Sztrákos and

Steurbaut, 2007). The lowermost seven samples (la-

belled L1 to L7) have been collected along the eastern

edge of the main quarry front (see Fig. 4). They come

from thin marly levels within an essentially lithified

interval, except for sample 1, which originates from a

soft calcareous pebble within the basal conglomerate A.

The remainder of the sample set (L8 to L32) was taken

along the western edge, from the base of a small

platform upward (Figs. 4 and 5). E. Steurbaut collected a

series of additional samples (labelled bis) in that part of

the section in April 2006 (Fig. 6).

In September 2002 K. Sztrákos also carried out the

stratigraphical logging and sampling of the Bidart

section (details in Sztrákos and Steurbaut, 2007). The

uppermost 7 samples (Bt14 to Bt20) from the most

northern undisturbed part of the section are discussed in

the present paper (Fig. 3).

Samples for foraminiferal analysis were processed

following standard micropaleontological procedures.

Quantitative analyses are based on estimations using

the following 3 categories: r (rare) = a few specimens,

c (common) = a few tens of specimens and f (frequent) =

over fifty specimens (Table 2). The taxonomy adopted

here is that from Berggren and Norris (1997) and Olsson

et al. (1999), the biozonation is from Berggren et al.

(1995), taking into account the modifications by

Berggren and Pearson (2005).

Qualitative and quantitative calcareous nannofossil

investigation was carried out using standard procedures

as described in Steurbaut and King (1994). About two

square centimeters of glass-slide have been examined

for each sample, using a Zeiss light microscope at 1000×

or 1250× magnification. The best-preserved and richest

associations have been examined with a Scanning

Electron Microscope at the Royal Belgian Institute of

Natural Sciences (RBINS). Martini's (1971) standard

Paleogene calcareous nannofossil zonation (traditional-

ly abbreviated to NP zones) and the high-resolution low

latitude zonation of Varol (1989) are applied here. The

taxonomy is essentially from Perch-Nielsen (1985),

taken into account subsequent modifications by Varol

(1992: Sullivana).

The calcareous nannofossil material is stored in the

collections of the RBINS (Brussels, Belgium). The

sieved residues from the foraminiferal investigation

(including the figured foraminifera) are temporarily kept

in the collections of Sztrákos (see address above), but

from 2008 on, will be permanently stored in the

collections of the “Muséum de Paris”.

Fig. 4. Lithological succession and position of samples in the eastern sector of the Loubieng quarry (anno, 2002).



4. Results

4.1. Calcareous nannofossils

4.1.1. Biozonation

The Late Danian and Early Selandian nannofossil

associations in SW France (Loubieng and also Bidart)

are difficult to link up with Martini's (1971) standard

calcareous nannoplankton zonation because of the

latitudinal asynchronous distribution of the marker

species Ellipsolithus macellus. The latter, the lowest

occurrence (LO) of which defines the base of Martini's

Zone NP4, seems to be a thermophile taxon with a

temperature-controlled dispersal. It is consistently and

commonly present in the Tethyan Realm from the base

of NP4 onward (Steurbaut et al., 2000; Guasti et al.,

2006), dated as 62.2 Ma (Berggren et al., 1995), but is

supposed to enter the North Sea Basin only several

million years later. This assumption is based on its

common occurrence in various Ypresian NP11 associa-

tions (∼53 Ma) of Western Europe (Aubry, 1983;

Steurbaut, 1991; Bignot, 1994; Steurbaut and King,

1994), after a period of extreme rarity throughout the

Paleocene (recorded from the Herne Bay section only,

dated as NP8 at ∼57 Ma, Aubry, 1983; Steurbaut,

1998). Its presence in the Danian of the North Sea Basin,

based on the identification of 2 specimens from

Denmark (Perch-Nielsen, 1979, reconfirmed in Perch-

Nielsen and Hansen, 1981) is regarded with caution, as

it has never been reported subsequently in that time

interval (Van Heck and Prins, 1987; Varol, 1989;

Steurbaut, 1998; Lottaroli and Catrullo, 2000; Clem-

mensen and Thomsen, 2005).

The low latitude zonation of Varol (1989) allows

much more refined interpretations of the nanno-

associations, NP4 being subdivided into 7 zones-

Fig. 5. Lithological succession and position of samples in the western sector of the Loubieng quarry.



subzones. This zonation is easily correlated with

Martini's zonation as the First Appearance Datum

(FAD) of E. macellus and the FAD of Fasciculithus

tympaniformis, respectively defining the base and the

top of NP4, are used as zonal boundary markers in both

zonations.

The lowest occurrence (LO) of E. macellus and the

HO of Neochiastozygus imbriei, defining Varol's

NTp5B/NTp5C and NTp6/NTp7 zonal boundaries

respectively, are coinciding in the Aquitaine Basin

(both recorded in sample Bt17) (Table 1). Comparison

of other nannofloral and microfaunal components in the

different areas studied indicates that this coincidence is

not due to the presence of a major hiatus. It just results

from the considerably time lag between the initial

appearance of E. macellus in the Tethyan Realm

(62.2 Ma) and its earliest occurrence in the Aquitaine

Basin (estimated at 60.95 Ma). This time lag approx-

imates 1.25 m.y., applying the time scale of Berggren

et al. (1995).

Varol's zonation seems to be applicable to the

Aquitaine Basin as all its relevant index taxa are

recognised in the nanno-associations of Bidart and

Loubieng. However, identification and calibration of

Varol's zones are not so straightforward as might be

thought, because most of these index taxa are very rare

in the lower part of their range (e.g. Chiasmolithus

edentulus, Sphenolithus primus, see below) or are

represented by small atypical specimens (Chiasmolithus

edentulus). There is no discrepancy between the distribu-

tion of the marker species in the Aquitaine Basin and the

Turkish Kokaksu Section, used as reference section in

Varol's zonation, if the term “first occurrence” is not used

in its strict sense, the record of the very first, often isolated

specimen (LO), but in a broader context, the start of the

consistent (LCsO) or common occurrence (LCO) of the

Fig. 6. Detailed lithology of the upper Lasseube Formation and the lower Pont-Labau Formation in the western sector of the Loubieng quarry (anno,

2006).



species. In Aquitaine, the LCO of C. edentulus coincides

with the LO of small Fasciculithus spp. (both in L10) and

precedes the LCsO of S. primus (L12) just as in Varol's

zonation sequence. However, in the Aquitaine Basin the

first few C. edentulus (interval L4 to L9) and S. primus

(L1) are known from older levels, implying that isolated

specimens can be recorded earlier, below Varol's so-

called “first appearance” levels.

The upper part of the Bidart section (Bt14–Bt20) is

attributed to Varol's interval NTp6- NTp7A, because of

the presence of E. macellus, the presence of N. imbriei

(up to Bt17) and the absence of Fasciculithus. This

Table 1

A time-calibrated sequence of calcareous nannofossil and planktonic foraminiferal events in the Danian/Selandian boundary interval in SWAquitaine

(ages after Berggren et al., 1995; Berggren and Pearson, 2005)

Events Planktonic foraminifera Calcareous nannofossils Location Age in

MaNr Nature Taxon Nature Taxon Bt/L

E1 LCsO Praemurica uncinata Bt 14 (61.2)

E2 LO Neochiastozygus imbriei Bt 14

E3 LO Morozovella angulata Bt 16 61.0

E4 LO Ellipsolithus macellus Bt 17 (62.2)⁎

E5 HO Neochiastozygus imbriei Bt 17

E6 LO Morozovella conicotruncata Bt 18 60.9

E7 HCO Praemurica inconstans Bt 19

E8 HCO Praemurica uncinata Bt 20

E9 LO Sphenolithus primus L 1 60.6

E10 LO Fasciculithus magnus L 2

E11 LO Fasciculithus magnicordis L 3

E12 LO Chiasmolithus edentulus L 4 (60.7)⁎

E13 HO Fasciculithus magnus L 4

E14 LO Acarinina strabocella L 6 60.5

E15 HO Praemurica inconstans L 7

E16 HO Morozovella praeangulata L 8

E17 LCO Morozovella angulata L 10

E18 LCsO Small Fasciculithus spp. L 10

E19 LCsO Chiasmolithus edentulus L 10

E20 LCsO Sphenolithus primus L 12

E21 LO Neochiastozygus perfectus L 12

E22 LO Ellipsolithus distichus L 12

E23 LO Fasciculithus vertebratoides L 12

E24 LO Igorina albeari L 17 60.0

E25 LO Morozovella apanthesma L 17

E26 HO Fasciculithus magnicordis L 19

E27 LO Morozovella velascoensis L 26 60.0

E28 LO Fasciculithus billii L 27

E29 LO Fasciculithus involutus L 27

E30 LO Fasciculithus janii L 27

E31 LO Fasciculithus ulii L1 bis 59.9

E32 HCO Braarudosphaera bigelowii L1 bis

E33 LO Subbotina velascoensis L 28

E34 LO Bomolithus elegans L 28

E35 LO Toweius sp. 1 L 28

E36 LO Large Neochiastozygus perfectus L 28

E37 LCsO Fasciculithus janii L 28

E38 HO Morozovella conicotruncata L 28

E39 HCO Parasubbotina varianta L 29

E40 LO Ellipsolithus bollii L 29

E41 LO Toweius tovae L 31

E42 LO Fasciculithus pileatus L 31

E43 LO Scapholithus apertus L 31

E44 LCsO Fasciculithus involutus L 31

E45 HO Morozovella angulata L 31

E46 LCO Fasciculithus pileatus L 32

E47 LO Fasciculithus tympaniformis L 32 59.7



interval corresponds to the lower middle part of

Martini's NP4 (Fig. 8).

The lower part of the Lasseube Formation in the

Loubieng quarry (covering samples L1 to L9), although

almost completely devoid of the NP4 marker species

E. macellus (1 specimen in L8) was definitely deposited

during Biochon NP4. It contains isolated specimens of

C. edentulus (1 specimen in L4) and of Sphenolithus

primus (a few specimens in L1 to L4) and is attributed to

zone NTp7A because of the absence of N. imbriei and

the absence of small Fasciculithus spp. (e.g. F. varolii

n. sp.). The presence of S. primus and the large

F. magnus suggests that it is slightly younger than the

top of the Bidart section. The remainder of the Lasseube

Formation and the major part of the exposed Latapy

Member also belong to NP4. This upper NP4 interval

can be subdivided into 4 subzones on the basis of the

LCO of C. edentulus, coinciding with the LO of

F. varolii (sample L10), the LCsO of Sphenolithus

primus (L12), the LO of Fasciculithus ulii (L1bis) and

the LO of Fasciculithus pileatus and the LCsO of

F. involutus (L31), marking the lower boundaries of

Varol's NTp7B, NTp8A, B and C respectively (Fig. 8).

The LO of Fasciculithus tympaniformis, defining the

base of Varol's NTp9 and Martini's NP5 was identified

in the topmost sample of the Latapy Member (L32).

4.1.2. Nannofossil evolution and major lineages

The nannofossil record at Bidart and Loubieng is

marked by a series of first occurrences, indicating that

the Mid-Paleocene calcareous nannofossil renewal,

defined by Aubry (1998) as an essentially increase in

generic diversification, is not a minor phenomenon as

originally thought. In a time span of about 0.9 million

years 4 genera emerge in the fossil record, in

chronological order Sphenolithus, Fasciculithus, To-

weius and Pontosphaera with a total of 19 species

occurrences (Table 1). Disappearances are less frequent

and essentially on the specific level (Neochiastozygus

eosaepes, N. imbriei, F. magnus, etc.).

4.1.2.1. Sphenolithus. S. primus, the oldest represen-

tative of the genus, first appears in sample L1, slightly

predating the LO of the genus Fasciculithus (L2). It is

poorly represented in the lowermost part of its range

(a few specimens in interval L1–L4). Its consistent

presence from L12 onward (1 to 2% of the association)

is considered to represent the NTp7B–NTp8 boundary.

After a short abundance peak in the upper part, but not

the top of NP 4 (L24-L26: between 12% and 25%), its

number decreases again to normal proportions (1 to 3%)

(Fig. 7).

4.1.2.2. Fasciculithus. The Danian–Selandian transi-

tion at Loubieng is a primary source for unraveling the

early evolutionary history of the genus Fasciculithus. The

origin of the genus is unclear, but phylogenetic relation-

ships with Markalius (Perch-Nielsen, 1977, 1981) or

Biantholithus (Aubry, 1998) are the most successful

among the postulated hypotheses. The first Fasciculithus

species encountered at Loubieng is F. magnus (L2). It

occurs in a thin interval (L2–L4) and is generally

accompanied by the much rare F. magnicordis (L3–L4).

The range of F. magnus is generally very short and can

easily be overlooked. In Tunisia it has been recorded at the

top of Zone NTp6 in the Aïn Settara section (Van

Itterbeeck et al., 2007). The small form F. varolii is the

next representative in the Fasciculithus sequence. It co-

occurs with F. chowii in sample L10. The latter,

pinpointed in many sections in Turkey, Spain and Tunisia,

announces the start of the consistent occurrence (LCO) of

the genus Fasciculithus throughout the Tethyan Realm. It

represents the first diversification event of the genus,

which slightly postdates the LO of Acarinina strabocella,

estimated at 60.5 Ma. The second diversification event,

marked by the LOs of F. billii, F. involutus and F. janii,

has been identified in sample L27. It is slightly prior to the

LO of F. ulii (L1 bis), dated at 59.9 Ma. Between the first

and second diversification event, the number of Fasci-

culithus specimens decreases from around 3% (L10 to

L12) to almost nil (from L24 onward). Important Fasci-

culithus events within this interval are: the LO of

F. vertebratoides n. sp. (L12) and the HO of

F. magnicordis (L19). The third event, pinpointed in

sample L28, is a merely quantitative phenomenon,

corresponding to the start of a bloom of Fasciculithus

(increase from ∼0.5% to 3% of the total number of

nannofossils). These high species diversity and high

quantitative percentages are consistently present in the

overlying samples (L29 to L32) and seems to be

characteristic of the top of NP4 and the base of NP5.

F. involutus is consistently present from the top of NP4

onward (L 31). The LO of F. tympaniformis, defining the

base of NP5 (L32), seems to coincide with a substantial

rise in F. pileatus (from less than 0.5% to 2.5%).

4.1.2.3. Toweius. The small Toweius forms have not

systematically been identified on the specific and the

generic level. They were grouped into the taxon

Prinsiaceae, because of the rather poor quality of some

of the nannofossil assemblages, hampering the identi-

fication and the exact estimation of the distibution of the

species. T. pertusus is present in L12, although its LO is

difficult to pinpoint because of preservation problems. A

large form (Toweius sp. 1) was recorded in L28, two



Fig. 7. Quantitative calcareous nannofossil distribution across the Danian/Selandian boundary in the Loubieng quarry (•=present, but not found in counts).

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others (Toweius sp. 2 and T. sp 3) in the overlying

samples L2bis to L8bis, whereas the large Toweius

tovae is consistently present from L31 upward.

Apparently, the major diversification event of the

genus Toweius took place around 59.8 Ma, during late

Biochron NP4. Toweius eminens has not been recog-

nised, indicating that the top of the Loubieng section

predates its first appearance, known to occur in the

middle of the Latapy Member (Steurbaut and Sztrákos,

2002).

4.1.2.4. Pontosphaera. This taxon is extremely rare in

the Danian–Selandian transition of the Aquitaine Basin.

Its first and only representative (one single specimen) is

recorded from L29.

4.1.2.5. Chiasmolithus edentulus. Small isolated spe-

cimens have been observed at the base of the Loubieng

section (2 specimens in L4). It is consistently present

from L10 onward, although in low numbers.

4.1.2.6. Neochiastozygus perfectus. The biostratigra-

phical relevant species N. perfectus, first recorded in

L12, is represented by rather small specimens in the

lower part of its range (Lmax=7 μm). Larger forms

(Lmin=8.5 μm) make their entry in L28.

4.1.3. Paleoenvironmental changes

Braarudosphaeraceae are consistently represented in

the upper Bidart section and in the Loubieng section

(Fig. 7). The genus Braarudosphaera, including B.

alta, B. bigelowii and B. discula, remains abundant

throughout the Lasseube Formation, although with a

series of fluctuations. Its distribution pattern is marked

by high values (12 to 20%) in interval Bt14–L2. It

presents a slight decrease (5 and 10%) in interval L3–

L9, a sudden increase in interval L10–L19 (15% to

24%) and a return to about 10% in the top of the

Lasseube Formation (L24 to L1bis) (Fig. 7). A sharp

and major decrease in abundance is recognised at the

base of the Pont-Labau Formation (Latapy Member)

(from 10% to less than 1%). Micrantholithus is less

abundant in the studied interval. It is not continuously

present in the Lasseube Formation, never exceeding

more than 3%. It is absent in the Latapy Member.

As Braarudosphaeraceae are known to prefer hyposa-

line coastal waters (Bukry, 1974; Moshkovitch and

Ehrlich, 1982), changes in their abundance patterns

indicate major fluctuations in water mass parameters

(essentially paleosalinity). The almost complete disap-

pearance of Braarudosphaeraceae at the boundary

between the Lasseube Formation and the Pont-Labau

Formation (Latapy Member) points to a sudden return to

normal salinity, after a substantial long period of

hyposaline conditions. Apparently, the Loubieng area

was suddenly deprived of freshwater influence. This

suggests a major decrease in precipitation or landward

shift of the coastline, related to a major sea-level rise.

4.2. Foraminifera

4.2.1. Planktonic foraminiferal zonation

The planktonic foraminiferal zonation of Berggren

et al. (1995) (consisting of the traditionally abbreviated

P zones) is applicable to the Danian and Selandian of the

Aquitaine Basin, without any special adaptation. Mor-

ozovella angulata, the lowest occurrence (LO) of which

defines the P2/P3a boundary, is recorded in sample Bt16

(Table 2). Igorina albeari is only rarely and inconsis-

tently represented. Its LO, defining the P3a/P3b

boundary, is recorded in sample L17. Not a single

specimen of Globanomalina pseudomenardii was en-

countered, suggesting that the top of the Loubieng sec-

tion is still within P3b.

4.2.2. Major biostratigraphic markers

All the foraminiferal taxa recorded in the upper

Bidart and the Loubieng sections, planktonic as well as

benthic, have been listed and figured by Sztrákos

(2005a), as part of a general study of the lower

Paleogene foraminifera of southern Aquitaine. Their

distribution reveals strong diversification of the plank-

tonic groups during Late Danian and Early Selandian

time, marked by rapid evolution within the muricate and

photosymbiotic lineages Acarinina, Morozovella and

Igorina, and disappearance of Praemurica (Table 2).

The planktonic foraminiferal associations are marked by

a series of appearances (LO, LCsO and LCO) and

disappearances (HO), which seem to have a substantial

biostratigraphic potential. The events (16 in total), their

position and age are summarised in Table 1. The LO of

Morozovella velascoensis, dated at 60.0 Ma, which is

major correlative event within the Tethyan realm is

slightly prior to the second diversification within the

genus Fasciculithus.

Changes within the benthic faunas are less conspic-

uous. According to Sztrákos (2005a) only three species

among the benthic foraminifera have biostratigraphic

interest in the D/S boundary interval of Aquitaine

(Tritaxilina cubensis and Thalmanitta madrugaensis

already present at the base of the Loubieng section, and

Svenia bulbosa, first appearing in L28). However, these

are too rare and too inconsistently present at Loubieng in

order to allow biostratigraphic resolution.



Table 2

Quantitative planktonic foraminiferal distribution across the Danian/Selandian boundary in SWAquitaine

Planktonic

foraminifera

Bidart samples Loubieng samples

B 14 15 16 17 18 19 20 1 2 3 4 5 6 7 8 9 10 11 11b 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29b 30 31 32 32b

Parasubbotina

pseudobulloides

B f c c f f f f r 1 r f c 1 r r f f c r c c c c c c f c c r c r r c c f r r r c

Subbotina

triloculinoides

B c r c c f c c f r r r f c c f r r c r r c f c c c c c c c c c c c c r c

Chiloguembelina

sp.

B 1 r r r

Praemurica

uncinata

B r r f rR 1R 1R

Praemurica

inconstans

B r c c r f r 1

Globanomalina

compressa

B r r r r r

Subbotina

triangularis

B c r r r r c r r r c c r c f c c c c c c c c c c c r c

Globanomalina

ehrenbergi

B r r c r r 1 r r r r r r r r r r r r r r r r r r r r r

Chiloguembelina

midwayensis

B r 1

Parasubbotina

varianta

r r r r c c 1 1 r r r c c r r 1 r r r r r r r c c r r r

Morozovella

praeangulata

r r r 2 r 1

Morozovella

angulata

c r r r r 2 2 1 r r r c c r f c c c c r c c c c c c c c f c c r r

Morozovella

conicotruncata

r r r r r r r r r r c c

Acarinina

strabocella

1 1 1 r r 2 r r

Subbotina sp. r r r

Igorina albeari r=rare 1 1 1 r r r r

Morozovella

apanthesma

c=common 1 r r r c c c c r r c r r r

Igorina pusilla f=frequent 1 1

Morozovella

velascoensis

B=also below f c c r

Subbotina

velascoensis

R=reworked r r r r r

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4.2.3. Abundance patterns

The planktonic foraminiferal faunas of the studied

sections are dominated by 4 genera, two of which,

Subbotina and Parasubbotina, are abundantly present

throughout the entire interval. The quantitative distri-

bution of the other two genera, Praemurica and Moro-

zovella, allows the Danian/Selandian boundary interval

of S Aquitaine to be subdivided into three major

planktonic foraminiferal assemblages (Fig. 8). The

lowermost Praemurica assemblage, occurring in the

upper part of the Bidart section, is characterised by

common to frequent occurrences of P. uncinata and

Fig. 8. Integrated stratigraphy of the Danian/Selandian boundary interval in SWAquitaine with positioning of the major calcareous nannofossil and

foraminiferal events.



P. inconstans, and contains rareMorozovella. The middle

mixed Subbotina–Parasubbotina assemblage is recorded

in the lower part of the Loubieng section. It is dominated

by both nominative genera and contains only rare Moro-

zovella and almost no Praemurica (a few specimens in

lowermost sample L1). The upper Morozovella assem-

blage is dominated by Morozovella, Subbotina and Par-

asubbotina, with almost equal proportions, and is

completely devoid of Praemurica (except for a few

reworked specimens). The other surface dwelling taxa,

such as Acarinina and Igorina are poorly represented in

S Aquitaine. Acarinina is inconsistently recorded in the

Loubieng section and only be very low numbers. Igorina

is restricted to the upper part of this section, and occurs

only inconsistently and rarely. Both have not been

recorded in the Bidart section. The deeper water taxon

Globanomalina is present in most of the samples. It is

recorded in very low quantities, except for sample Bt18,

where it is quite common.

Most of the benthic foraminifera range throughout

the studied section, including the mesobathyal forms

Stensioeina beccariiformis and Osangularia velascoen-

sis. A few specimens show substantial abundance

differences, allowing a three-fold subdivision of the

benthic foraminiferal fauna. The lowermost assemblage

B1 and B2 are recorded in the Lasseube Formation.

High numbers of Textularia plummerae, Cibicidoides

alleni and Gavelinella abudurbensis mark assemblage

B1 (Fig. 8). These taxa are rare or lacking in the

overlying B2 assemblage (sample L10 and higher),

which on the contrary is richer in Bulimina and in An-

gulogavelinella avnimelechi. The B3 assemblage,

characteristic of the Latapy Member, shows a strong

increase in Gyroidinoides globosa and G. subangulata

and in the deepwater form Nuttallides truempyi.

4.2.4. Paleoenvironmental interpretation

Subbotinids, known to prefer living within or below

the termocline, are abundantly present throughout the

studied interval. Their co-occurrence with rare globa-

nomalinids, also deepwater dwellers, indicates the

presence of deepwater settings in the D/S boundary

interval in S Aquitaine. This is corroborated by the

persistence of mesobathyal benthic foraminifera, such as

S. beccariiformis, O. velascoensis and N. truempyi,

throughout the interval.

The strong increase of morozovellids in the upper

10 m of the Lasseube Formation (from L10 onward),

associated with slight differences in the benthic

foraminiferal fauna (occurrence of B2 assemblage),

suggests a shallowing of the paleoenvironment, al-

though still within the bathyal range. The typical

representatives of the surface mixed-layer zone, such

as the frequent morozovellids and the rare acarinids and

igorinids, disappear at or in the lower part of the Pont-

Labau Formation. This major change in planktonic

foraminifera coincides with a substantial increase of the

mesobathyal benthic form N. truempyi, referring to

substantial deepening of the basin, with paleodepths

below 600 m.

4.3. Changes in cyclicity patterns

The Lasseube Formation represents a limestone-

dominated stacking pattern, consisting of a series of

limestone beds and thin marly intercalations. The

proportion of marl in the marl/limestone couplets

increases upward in the formation. The crowded

bundles, limestone beds alternating with marly joints,

dominate in the lower part of the formation (Figs. 5

and 8). Open bundles with clear marly interbeds develop

in the upper part of the Lasseube Formation (from

sample L10 on), with increasing thickness of the marly

portion in upward direction. This limestone/marl

cyclicity changes abruptly at the base of the overlying

essentially marly Latapy Member, which marks the base

of the Pont-Labau Formation in the Orthez area.

4.4. Red-coloured beds

In the Loubieng quarry these beds are restricted to the

upper part of the Lasseube Formation. They first appear

in-between sample L17 and L18 and are irregularly

alternating with grey-coloured beds up to the top of the

Formation (Figs. 5 and 6). The uppermost red level

occurs within the base of the Pont-Labau Formation,

about halfway between stone levels F and G (Fig. 6).

The red colour is probably due to the presence of

oxidized Fe-bearing particles, introduced into the

sedimentation system through aeolian or hydrological

transport from an adjacent continental source.

5. Discussion

5.1. The Late Danian–Early Selandian depositional

history of S Aquitaine

Integration of micropaleontological and sedimento-

logical data from the upper Bidart and the Loubieng

outcrop sections reveals that the Late Danian–Early

Selandian depositional history of S Aquitaine is marked

by two significant geological events, which had

substantial repercussions on the biotic and sedimento-

logical evolution of the area. The first event (named



Fig. 9. North Sea Basin— Tethys correlations across the Danian/Selandian boundary.

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Aquitaine 1 or A1) occurred in the upper part of the

Lasseube Formation (base sample L10) at ca 60.3 Ma. It

led to the increase in Morozovella and in braarudo-

sphaerids, to the onset of a slight, but gradual influx of

siliciclastics in the depositional area, resulting in the

development of clear limestone-marl couplets and to the

formation of red-coloured beds. These changes point to

a shallowing sea-floor in the Loubieng area, although

probably still within epibathyal depths, and to approach

of the coastline (continental source). It points to

regressive conditions. The second event, occurring

400 k.y. later (A2 at 59.9 Ma), had a much more

pronounced effect, as shown by the disappearance of the

typical limestone-marl cyclicity and its replacement by

an almost exclusive siliciclastic sedimentation regime in

greater part of S Aquitaine (Fig. 9). The disappearance

of planktonic foraminifera of the surface mixed-layer

zone, and the increase in mesobathyal benthic forami-

nifera indicate deepening of the Loubieng depocentre.

The disappearance of braarudosphaerids witnesses the

return of normal salinity, due to disconnection of the

depocentre from freshwater sources as the coastline

shifted substantially landward. All these changes

suggest an abrupt reinforcement in subsidence in S

Aquitaine, initiating a major transgressive pulse. It is

coupled with an overwhelming influx of siliciclastic

material due to increasing uplift in certain tectonically

unstable sectors. Plate tectonic compression due to

collision of the African and European plates seemed to

have provoked major uplift in the central and eastern

Pyrenees (Baceta et al., 2007) and substantial subsi-

dence in adjacent northern areas (Steurbaut and

Sztrákos, 2002; Sztrákos, 2005a).

This major transgressive A2 event at 59.9 Ma, clearly

separating two different deposition systems (e.g. in the

Orthez-Pau area, the Lasseube Formation and the Pont-

Labau Formation), has since long been identified

throughout the Aquitaine Basin (Gubler and Pomeyrol,

1946; Kieken, 1974). It has led to the traditional twofold

subdivision of the Paleocene of Aquitaine, including a

lower system, known as the Dano-Montian or Danian,

and an upper system, termed Upper Paleocene,

Thanetian or even Landenian (Kieken, 1974).

5.2. North Sea Basin–Tethys correlations (Fig. 9)

Global correlation of the D/S boundary interval has

remained unsuccessful up to now because the major

biostratigraphically significant microfossil groups, such

as Acarinina, Morozovella and Igorina, among the

planktonic foraminifera, and sphenolithaceae and fasci-

culithaceae among the calcareous nannofossils, well-

known worldwide, including the Tethys, are not or only

rarely recorded in this interval in the North Sea Basin.

Moreover, through their endemic nature the biota in the

latter are quite different from these in the surrounding

world's oceans.

5.2.1. North Sea Basin

Clemmensen and Thomsen (2005) concluded on the

basis of a multidisciplinary investigation that the

transformation of the Danish Basin from a carbonate

to a siliciclastic basin across the Danian/Selandian

boundary involved 4 steps. These steps correspond to

substantial paleontological and lithological changes, as

the result of sea-level fluctuations in the northeastern

part of the North Sea Basin, which, according to these

authors, seemed to be primarily of eustatic nature. A

similar stepwise transformation has also been recog-

nised in the Belgian Basin (Steurbaut, 1998), although

its relation with other areas was not completely

understood at that time. The recent release of new

information from Denmark reveals that both the Danish

Subbasin and the Belgian Subbasin underwent an

analogous depositional history, allowing detailed inter-

regional correlation (see Fig. 9).

The first step in this shifting depositional regime

results from a considerable sea-level fall (∼50 m). It led

to the abrupt shift from bryozoan limestone to calcisiltite

in Denmark and from shallow marine shelly limestone

(the Mons Limestone) to fluviatile clays, lacustrine

marls and limestones in West Belgium (Hainin Forma-

tion) and to continental multicoloured clays with lignitic

lenses or fine sands in East Belgium (Opglabbeek

Formation). In Denmark step 1 is associated with major

biotic changes (decrease in planktonic foraminiferal

proportions and increase in braarudosphaerids). The

second step, corresponding to the Danian/Selandian

boundary in its traditional concept, is characterised by

the reinstallation of fully marine conditions, with the

start of the deposition of the Lellinge Greensand or

Kerteminde Marl in Denmark, depending on the

position in the basin. Similar deposits accumulated

simultaneously in NE Belgium, the transgressive

glauconitic calcareous Orp Sands in the shallow areas

and the Gelinden Marls in the somewhat deeper zones.

In both subbasins there is a considerable increase in

influx of land-derived material, probably originating

from erosion of the same source area, the uplifted

Scotland-Shetland landmass. The hyposaline Braarudo-

sphaeraceae seem to disappear almost completely from

the northeastern Danish part of the North Sea Basin at

that particular point in time. The third step, marked by

the replacement of in situ nannofossils by reworked



Cretaceous forms at the transition Lellinge Greensand–

Kerteminde Marl in Denmark, has also been identified

in Belgium, at the top of the Orp Sands. The fourth step,

the abrupt shift from marl to non-calcareous or slightly

calcareous clay, has not been recognised as such in

Belgium because of fundamental differences (paleotem-

perature, paleodepth, circulation patterns, degree of

isolation, etc.) between both subbasins. In Belgium this

shift to non-calcareous sedimentation is much more

gradual. A first decrease in carbonate is recognised at

the boundary between the Gelinden Marl (white chalky

marl with carbonate content between 80 and 90%) and

the overlying Maaseik Clay (grey clayey marl with

carbonate content around 60%). A second more

conspicuous change is observed in the lower part of

the overlying Waterschei Clay (carbonate content drops

to 25%; Steurbaut, 1998).

5.2.2. Aquitaine Basin

The sea-level fall within the upper part of the

Lasseube Formation (event A1) is correlated with step 1

in the North Sea Basin. This fall was not sufficiently

large to provoke substantial differences of the bathyal

depositional regime in western Aquitaine. It just led to

considerable changes in planktonic and benthic life and

in an increase in land-derived material. The transgres-

sive event A2 is linked to step 2 in the North Sea Basin

because of similar sedimentological (abrupt change in

sedimentation pattern because of deepening and of

major influx of land-derived material) and biotic

(disappearance of braarudosphaeraceae) changes. Steps

3 and 4 have not been identified in the Aquitaine Basin.

5.2.3. Zumaia (N Spain)

The lithological stacking of the limestone/marl

couplets in the D/S boundary interval at Zumaia is

identical to that in the southern part of the Aquitaine

Basin (see above, Section 4.3). There is an abrupt shift

from a limestone-dominated unit (the so-called

“crowded member” of Baceta et al., 2006) to a

“stratified member” with clear marlstone intercalations

at about 9.5 m below the top of the “Danian Limestone

Formation”. This level is very close to the LO of small

Fasciculithus spp. and therefore can be correlated with

the same lithological event in the Aquitaine Basin

(event A1). The contact between the Danian Limestone

Formation and the marly base of the Itzurun Formation

corresponds to major biotic changes, also recognised at

event A2 in the Aquitaine Basin (abrupt decrease in

braarudosphaerids, LCsO of F. janii). In both areas

this lithologic junction is located at the top of NP4,

between the bracketing events of the LO ofMorozovella

velascoensis (below) and the LO of Fasciculithus

tympaniformis (above).

5.2.4. Tunisia

The D/S boundary interval in Central and West

Tunisia is marked by a marly depositional regime. It is

interrupted by complex channel systems with glauconite

infill in a single thin interval (level T1). This condensed

interval with several short breaks in sedimentation is due

to a considerable sea-level fall. It separates outer shelf

(∼150 m depth) from inner shelf deposits (∼100 m

depth) in the Sidi Nasseur section, close to Kalaat Senan

(Guasti et al., 2006; Van Itterbeeck et al., 2007). It

coincides with the entry of small Fasciculithus and the

start of the common occurrence of Morozovella

(including M. angulata). Because of similarity of biotic

changes this major event, which was correlated with the

D/S boundary by Steurbaut et al. (2000) and Guasti et al.

(2006), adopting the recommendations of Berggren

et al. (1995), must be equated with event A1 in the

Aquitaine Basin. The latter, also related to a sea-level

fall, is believed to be coeval with step 1 in the North Sea

Basin. Thus, the major lithological event in Central

Tunisia, coinciding with the P3a/P3b planktonic fora-

miniferal boundary according to Guasti et al. (2006), is

definitely older and unrelated to the traditionally defined

Danian/Selandian boundary. The subsequent steps 2

to 4, widely recognisable in the North Sea Basin, have

not been identified in western Tunisia.

Sedimentation conditions are substantially different

in East Tunisia (Fig. 1), as shown by the stratigraphic

succession of the Jbel M'Daker (MDKB) section, a few

km west of Enfidaville. The Danian is much more

condensed and consists of an 8.2 m thick alternation of

limestones and marls. It is unconformably overlain by

grey marls and marly clays, of which the age was not

well constrained up to now. Calcareous nannofossil

investigation allowed for the first time detection of a

major hiatus in that part of the Tunisian Basin,

encompassing the late part of the Danian and the entire

Selandian (interval from top of NP2 to base of NP6 is

missing).

5.2.5. Egypt

The investigation of the Qreiya outcrop sections in

Central Egypt reveals the presence of several omission

surfaces in the top part of the essentially greyish shaley

Lower Dakhla Formation, the lowermost of which (S1)

seems to be consistent throughout the Nile Basin. Deep

vertical and oblique bioturbations originate from this

surface and penetrate in the underlying deposits (Fig. 9).

Surface S1 is overlain by 8 cm of brownish heterogeneous



shale rich in fish debris and by 15 cm of dark brown

laminated shale. The boundary between the grey shaley

lower Dakhla Formation and the overlying beige-

coloured chalky marls of the upper Dakhla Formation is

also marked by an omission surface (S2) with several

bioturbations.



Speijer (2003) recorded a major paleoenvironmental

shift at surface S1 in the Aweina section, marked by

substantial changes in the foraminiferal assemblages.

The dominant occurrence of Neoeponides duwi in the

organic-rich layer, overlying surface S1, referred to as

the “Neo-duwi event”, was believed to result from a 50

to 100 m shallowing of the depositional area. Speijer

(2003) associated surface S1 with a sequence boundary

and with the D/S boundary.

Preliminary studies of the nannofossil assemblages

from the Egyptian sections led to the positioning of the

first small Fasciculithus taxa (e.g. F. chowii). This

lowest consistent occurrence (LCO) of Fasciculithus is

recorded about 1.20 m below S1 (Sprong et al., in press).

It is coinciding with the LCO of Chiasmolithus

edentulus and with the start of rather frequent Ponto-

sphaera spp. Identical associations have been recog-

nised in West Tunisia at glauconitic level T1. The

boundary between the shaley lower Dakhla Formation

and the marly upper Dakhla Formation coincides with a

major quantitative influx in calcareous nannofossils

(doubling of number of specimens/mm2), characterised

by the LCsO of Fasciculithus janii and the rare

occurrence of Toweius tovae. It relates to a higher

productivity within the sea surface layers and to a

decrease in influx of siliciclastic material, which seems

to point to a transgressive pulse. This boundary is coeval

with the boundary between the Lasseube Formation and

the Pont-Labau Formation in Aquitaine (event A2),

dated as 59.9 Ma, being both bracketed between the LO

of Morozovella velascoensis and the LO of Fascicu-

lithus tympaniformis.

5.2.6. Sea-level changes

The present sedimentological and micropaleontolo-

gical investigation carried out along a N–S transect from

North Sea Basin to southern Tethys has allowed

deciphering of the amplitude, timing and nature of the

depositional events, marking the Danian–Selandian

transition. It shows that the 4 phases of sea-level

change, identified in the D–S transition in the type area,

are not all 4 primarily caused by eustacy, as previously

thought (Clemmensen and Thomsen, 2005). On the

contrary, only the sea-level changes associated with

steps 1 and 2 of Clemmensen and Thomsen (2005) have

been consistently identified throughout the investigated

area. Step 1, marked by a sea-level fall, is everywhere

characterised by a discontinuity and substantial paleoen-

vironmental change, despite major latitudinal and

paleobathymetric differences. It is interpreted as a

major sequence boundary. Up to now, we do not know

if this sea-level fall is a global phenomenon, as it has

only been identified in the east Atlantic–North African

realm, in basins with a common tectonic history. The

sedimentological response to this plate tectonic event

strongly diverges from area to area and is not equally

pronounced. The shallow marine areas, such as the

Belgian and the Danish Basins (complete change of

depositional regime) were much more affected than the

intermediate (Tunisia and Egypt, presence of disconti-

nuity) and the deeper settings (Aquitaine and Zumaia).

However, a 40 to 50 m sea-level drop seems to be

compatible with the palaeoenvironmental data recorded

along the studied transect, suggesting a major tectonic

uplift pulse at ∼60.3 million years ago in that part of the

globe.

Step 2 of Clemmensen and Thomsen (2005),

corresponding to a major shift from carbonate to

siliciclastic depositional regime with major deepening

of the sea-floor, has been recorded throughout the North

Sea Basin, in Aquitaine and in N Spain, but seems not to

have left any clear sedimentological imprint in the

Tunisian areas. Recent investigations in Central Egypt

provide evidence of a major change in depositional

regime in the Nile Basin, coeval to the phenomena in the

North Sea Basin, but of inverse nature, siliciclastics

shifting to carbonates. Apparently, the paleoenviron-

mental shift, defining step 2, which coincides with the

traditionally defined Danian/Selandian boundary and

with the newly designated GSSP for this boundary

(Zumaia), appears to be detectable on a widespread

scale (global?). The micropaleontological and sedimen-

tological data point to a major transgression, of which

the origin is not well understood up to now. The sudden

almost complete disappearance of the hyposaline

braarudosphaeraceae in different basins throughout

Plate I. 1, Acarinina strabocella (Loeblich and Tappan, 1957), Loubieng L6, ×200. 2, Acarinina strabocella (Loeblich and Tappan, 1957),

Loubieng L29b, ×154. 3, Morozovella praeangulata (Blow, 1979), Bidart Bt16, ×171. 4, Morozovella angulata (White, 1928), Bidart Bt16, ×114.

5, Morozovella conicotruncata (Subbotina, 1947), Loubieng L7, ×114. 6, Morozovella velascoensis (Cushman, 1925), Loubieng L28, ×97. 7,

Morozovella apanthesma (Loeblich and Tappan, 1957), Loubieng L17, ×142. 8, Igorina albeari (Cushman and Bermudez, 1949), Loubieng

L29, ×200. 9, Globanomalina compressa (Plummer, 1927), Bidart Bt14, ×142. 10, Globanomalina ehrenbergi (Bolli, 1957), Bidart Bt17, ×114.

11, Igorina albeari (Cushman and Bermudez, 1949), Loubieng L17, ×171. 12, Parasubbotina varianta (Subbotina, 1953), Loubieng L29b, ×114.

13, Igorina pusilla (Bolli, 1957), Loubieng L17, ×171. 14, Igorina pusilla (Bolli, 1957), Loubieng L29, ×200. 15, Subbotina velascoensis

(Cushman, 1925), Loubieng L28, ×142.



Europe at the D/S boundary is believed to be due to the

interruption of freshwater influx, related to major

climatic changes (probably a substantial decrease in

precipitation). The difference in sedimentological sig-

nature between Europe (carbonates to siliciclastics) and

Egypt (siliciclastics to carbonates), originates from a

different tectonic history. Plate tectonic compression in

the Pyrenean area, due to collision of the W European

and African plates, caused uplift in the central and

eastern Pyrenees and major influx of siliciclastics in



northern (Aquitaine) and southern (N Spain) adjacent

areas. Similar movements seem to have occurred in the

northern North Sea Basin with uplift of the Scotland-

Shetland landmass, related to the opening of the

Northern Atlantic. The hyposaline braarudosphaeraceae

are virtually absent in the southern Tethys (Tunisia and

Central Egypt) indicating normal salinity conditions

throughout the D/S boundary interval. The transgressive

event, associated with step 2 in that area, coincides with

the deepening of the basin and the decrease in land-

derived siliciclastics.

The third step, marked by a major influx of

Cretaceous nannofossils, is a phenomenon that seems

to be restricted to the North Sea Basin. It is related to

inversion of various local Cretaceous subbasins during

the early Selandian, which in most places led to erosion

of several hundred metres of chalk. As it has no

correlative in more southern areas, it seems to be a

regional, tectonic North Sea Basin-related event.

Step 4 corresponds to a rather abrupt change from

marl to clay sedimentation in the Danish Subbasin,

suggested to have occurred in the later part of the early

Selandian (Clemmensen and Thomsen, 2005). It is

believed to result from the installation of colder and

acidic sea-bottom conditions, due to increasing water

depth and restricted water circulation. In Belgium the

transition from marl to clay occurred in two steps. The

first step corresponds to a 25% reduction of the

carbonate content, which took place during the late

Selandian, dated at 58 to 58.5 Ma. The second, marked

by a further 40% reduction of carbonate content

occurred in the early Thanetian at ∼57.5 Ma. Appar-

ently there is a general shift from marls to clays in the

North Sea Basin, although not simultaneously through-

out the Basin. Step 4 as defined in the Danish Subbasin

seems to be a local phenomenon.

5.3. The Loubieng section in light of the recent D/S

boundary decisions

The present investigation has shown for the first

time that the original D/S boundary criteria, defined in

the type area of Denmark as a major influx in

siliciclastics and a drastic decrease in braarudosphaer-

aceae proportions, cannot be identified outside the

European basins and that the major lithological and

paleoenvironmental shift in the Tethys area is not

coeval with the D/S boundary in the type area, as

previously thought (Steurbaut et al., 2000; Speijer,

2003; Van Itterbeek et al., 2007). This shift, coinciding

with the P3a/P3b planktonic foraminiferal boundary

and resulting from a tectonically induced sea-level fall

(major sequence boundary), is 400 k.y. older. It is

marked by the start of the consistent occurrence of

small Fasciculithus spp. and by the replacement of a

Praemurica-dominated by a Morozovella-dominated

planktonic foraminiferal association. As these biotic

phenomena are recorded on a widespread scale (except

North Sea Basin) they might help in the global

correlation of the D/S boundary interval and the

positioning of the sequence boundary, 400 k.y. prior to

the D/S boundary in the type area.

The present study also reveals that the Loubieng and

the Zumaia sections are the only currently known D/S

boundary sections, of which the microbiota shares

elements with that of the North Sea Basin and that of the

Tethys area, allowing global correlation. Both sections

are marked by a common depositional history, as shown

by the almost identical stratal succession and sequence

of bio-events. Both sections fulfil all necessary condi-

tions and recommendations for the establishment of a

Global Stratotype Section and Point (GSSP) for the

Danian/Selandian boundary. The final decision in

Plate II. The calcareous nannofossil specimens figured on Plates II and III, as well as the negatives of micrographs, are stored at the Royal Belgian

Institute of Natural Sciences (Brussels). Numbers (e.g. IRScNB b4975) refer to the collections of this institute. The following abbreviations are

used: Bt = Bidart, c.p. = cross-polarised light, D = diameter, H = height, L = Loubieng, Le = length, SEM = Scanning Electron Microscope, t.l. =

transmitted light and W = width. 1–3, Neochiastozygus imbriei Haq and Lohmann, 1976 — 1: Bt16, t.l., Le=6.4 μm, ×3125 (IRScNB b4967); 2:

Bt15, t.l., Le=5.6 μm, ×3125 (b4968); 3: Bt17, t.l., Le=6.0 μm×3125 (b4969). 4, Ellipsolithus macellus (Bramlette and Sullivan, 1961)—Bt18, c.p.,

Le=9.2 μm, ×2950 (IRScNB b4970). 5–6, Sphenolithus primus Perch-Nielsen, 1971— 5: L1, c.p.,W=5.2 μm, ×3650 (IRScNB b4971); 6: L3, c.p.,

W=4.8 μm, ×3750 (b4972). 7–12, Fasciculithus magnus Bukry and Percival, 1971 — 7: L2, t.l., W=12 μm, ×1420 (IRScNB b4973); 8: L3, c.p.,

W=13.5 μm, ×1700 (b4974); 9: L4, c.p.,W=12 μm, ×1750 (b4975); 10: L4, a=c.p., b=t.l.,W=12 μm, ×1500 (b4976); 11: L4, t.l.,W=12 μm, ×1500

(b4977); 12: L4, c.p.,W=12 μm, ×1600 (b4978). 13, Fasciculithus magnicordisRomein, 1979— L4, t.l.,W=8 μm, ×3000 (IRScNB b4979). 14–15,

Braarudosphaera bigelowii (Gran and Braarud, 1935) — 14: L27, a=t.l., b=c.p., D=18.4 μm, ×1630 (IRScNB b4980); 15: L5, t.l.,

D=17.0 μm, ×1700 (b4981). 16, Ellipsolithus macellus (Bramlette and Sullivan, 1961) — L27, c.p., Le=10 μm, ×3300 (IRScNB b4982). 17–18,

Fasciculithus varolii n. sp.— 17: L10, paratype, c.p., a=low focus, b=high focus, H=6.4 μm, ×1330 (IRScNB b4983); 18: L10, holotype, a=t.l.,

b=c.p.,H=5.6 μm, ×1520 (IRScNB b4984). 19–20,Fasciculithus ulii Perch-Nielsen, 1971— 19: L1bis, t.l.,H=5.6 μm, ×1700 (IRScNB b4985); 20:

L1bis, a=t.l., b=c.p., H=6.4 μm, ×1400 (IRScNB b4986). 21, Chiasmolithus edentulus van Heck and Prins, 1987— L27, c.p., Le=8.8 μm, ×1700

(IRScNB b4987). 22, Fasciculithus sp. — L32, c.p., H=5.6 μm, ×1520 (IRScNB b4988). 23, Toweius sp. 1 — L2bis, c.p., Le=8.0 μm, ×1440

(IRScNB b4989). 24, Toweius sp. 2— L8bis, c.p., Le=7.9 μm, ×1580 (IRScNB b4990). 25, Fasciculithus tympaniformis Hay and Mohler in Hay et

al., 1967 — L32bis, c.p., W=5.6 μm, ×1520 (IRScNB b4991).



favour of Zumaia was made during an International

Workshop of the Paleocene Working Group the 20th

June 2007. The members of the group unanimously

chose the base of the Itzurun Formation in the Zumaia

section as GSSP, because of a somewhat better and more

permanent accessibility of the outcrop (coastal section

versus quarry) and the wider gamut of scientific

information available (magnetostratigraphic and cyclos-

tratigraphic studies only currently present at Zumaia).

However, the fossil content is better preserved at



Loubieng, and the quarry section presents no major

structural displacements, as some parts of the Zumaia

section do (although not in the D/S boundary interval).

Exhibiting a permanent outcrop of 0.9 m.y. non-faulted

microfossil-rich continuous sedimentation and situated

in the same paleogeographic context as Zumaia, the

Loubieng section constitutes an excellent auxiliary

section for the D/S boundary. The good quality of its

microbiota allows definition of correlative D/S bound-

ary criteria for the Tethys area. The LCsO of F. janii, the

LO of Bomolithus elegans and the LO of Subbotina

velascoensis are coeval with D/S boundary criteria in the

type area, permitting identification of the D/S boundary

event on a global scale.

6. Conclusions

Forty-seven bio-events, of which 16 planktonic

foraminiferal and 31 nannofossil events are identified

in the Danian/Selandian boundary interval in SW

France, in the 1.5 m.y. period spanning the upper

Lasseube Formation and the lower Pont-Labau Forma-

tion. This sequence of bio-events, ranging from 61.2 Ma

to 59.7 Ma, has allowed to clarify the temporal and

spatial significance of the different depositional events

marking the D/S transition in its type area in the North

Sea Basin (the 4 steps or 4 phases of sea-level change of

Clemmensen and Thomsen, 2005) and to correlate these

throughout the S Tethys. Contrarily to what has been

postulated, only the two lowermost steps and not all 4

(Clemmensen and Thomsen, 2005), represent wide-

spread sea-level changes, due to plate tectonic adjust-

ments, whereas the second, corresponding to the D/S

boundary as defined in Denmark, is 400 k.y. younger

than the supposed D/S boundary in the southern Tethys

(Steurbaut et al., 2000; Speijer, 2003).

The first step, corresponding to a sea-level fall of the

order of 40 to 50 m and dated as 60.3 Ma, caused

considerably biotic and depositional changes in all areas

studied. It corresponds to 1. disappearance of bryozoa in

Denmark and installation of a continental depositional

regime in Belgium (e.g. the Hainin Formation, bearing

the oldest Tertiary mammals from Europe); 2. develop-

ment of channel systems with glauconite infill and

replacement of a Praemurica-dominated by a Morozo-

vella-dominated planktonic foraminiferal association in

Tunisia and 3. onset of a period of non-deposition and

the entry of a shallow marine benthic foraminiferal

association (the well-known Neo-duwi event) in Central

Egypt. The second step, dated as 59.9 Ma, corresponds

to a major transgressive event, which is accociated with

the deposition of the Lellinge Greensand in Denmark,

and hence, represents the D/S boundary. It corresponds

to fundamental changes in the Aquitaine Basin, as

shown by the replacement of limestone-dominated

(Lasseube Fm) by siliciclastic deposition (Latapy

Member of Pont-Labau Fm) and by the disappearance

of the hyposaline braarudosphaeraceae, events that are

simultaneously recorded in the North Sea Basin. The

sudden almost complete disappearance of this nanno-

fossil taxon in different basins throughout Europe at the

D/S boundary seems to indicate major climatic changes,

most probably a drastic decrease in precipitation. In

Central Egypt this step coincides with the boundary

between the shaley lower Dakhla Formation and the

marly upper Dakhla Formation. The third step, marked

by a major influx of Cretaceous nannofossils during the

early Selandian, is a regional tectonic North Sea Basin-

related event, whereas the fourth step, the abrupt change

from marl to clay sedimentation in the later part of the

early Selandian appears to be restricted to Denmark, and

thus, represents a local tectonic phenomenon.

The Loubieng section supplements the Zumaia

section, which, the 20th June 2007, was designated as

GSSP for the D/S boundary by unanimous decision of

the Paleocene Working Group. Because of its rich and

Plate III. 1–5, Fasciculithus vertebratoides n. sp. — 1: L31, paratype, a=t.l., b=c.p., W=7.5 μm, ×1670 (IRScNB b4992); 2: L12, paratype, c.p.,

a=high focus, b=low focus, W=6.8 μm, ×2800 (b4993); 3: L27, paratype, c.p., W=6.4 μm, ×2810 (b4994); 4: L27, paratype, t.l.,

W=8.4 μm, ×1670 (b4995); 5: L31, holotype, t.l., W=8.8 μm, ×1360 (IRScNB b4996). 6, Neochiastozygus perfectus Perch-Nielsen, 1971 —

L2bis, a=t.l., b=c.p., Le=8.8 μm, ×1590 (IRScNB b4997). 7–8, Ellipsolithus bollii Perch-Nielsen, 1977 — 7: L29, c.p., Le=10.5 μm, ×1620

(IRScNB b4998); 8: L31, c.p., Le=11.0 μm, ×1360 (IRScNB b4999). 9, Toweius sp. 2 — L31, t.l., Le=7.2 μm, ×1600 (IRScNB b5000). 10,

Fasciculithus involutus Bramlette and Sullivan, 1961 — L31, c.p., W=7.0 μm, ×1570 (IRScNB b5001). 11–15, Fasciculithus janii Perch-Nielsen,

1971 — 11: L28, c.p., W=8.8 μm, ×1930 (IRScNB b5002); 12: L29, c.p., W=7.2 μm, ×2780 (b5003); 13: L28, c.p., W=7.2 μm, ×3125 (b5004);

14: L29, c.p., W=8.4 μm, ×2860 (b5005); 15: L27, c.p., W=6.0 μm, ×3000 (b5006). 16, Toweius tovae Perch-Nielsen, 1971 — L6bis, t.l.,

Le=8.4 μm, ×1370 (IRScNB b5007). 17, Bomolithus elegans Roth, 1973 — L31, c.p., W=8.0 μm, ×2750 (IRScNB b5008). 18, Coccolithus

subpertusus (Hay and Mohler, 1967) — L28, c.p., D=11.2 μm, ×1420 (IRScNB b5009). 19, Ellipsolithus distichus (Bramlette and Sullivan,

1961) — L32, c.p., Le=9.6 μm, ×1560 (IRScNB b5010). 20, Scapholithus apertus Hay and Mohler, 1967 — L31, c.p., Le=4.0 μm, ×3375

(IRScNB b5011). 21, Fasciculithus vertebratoides n. sp. — L28, paratype, SEM, W=8.3 μm, ×2890 (IRScNB b5012). 22, Sphenolithus primus

Perch-Nielsen, 1971 — L32, SEM, W=5.5 μm, ×4180 (IRScNB b5013). 23–26, Fasciculithus pileatus Bukry, 1973 — 23: L32, SEM,

W=5.1 μm, ×3430 (IRScNB b5014); 24: L32, SEM, W=5.0 μm, ×4000 (b5015); 25: L32, a=c.p., b= t.l., H=7.2 μm, ×1530 (b5016); 26: L32,

c.p., H=6.0 μm, ×3000 (b5017).



well-preserved fossil content and continuous sedimen-

tation the Loubieng section constitutes an excellent

auxiliary section, forming a kind of intermediate station

between Zumaia and the rest of the world.

Acknowledgements

The authors wish to thank H. De Potter andW. Miseur

(RBINS) for providing graphical assistance. Thanks are

due to E. Molina and an anonymous reviewer for their

critical reading of the manuscript and helpful sugges-

tions. This research was financially supported by the

Royal Belgian Institute of Natural Sciences— Brussels

and by the “Fonds voor Wetenschappelijk Onderzoek

(FWO)— Vlaanderen” (grant G.0527.05).

Appendix A. Taxonomic remarks on the calcareous

nannoflora

The taxonomy adopted here is that of Perch-Nielsen

(1985), taking into account the modifications of Van

Heck and Prins (1987) and Varol (1992). The taxonomic

discussions are restricted to key-species with a doubtful

taxonomic record and to taxa that are new to science or

have been recognized for the first time. Species are

discussed in alphabetic order. Synonymy lists, if

present, only include the original citation, the citations

related to the same geographic area and those that gave

rise to subsequent erroneous interpretations. A full

taxonomic list of all nannofossil and foraminiferal taxa

cited in this paper is given in Appendix B. Abbrevia-

tions used: B = breadth, D = diameter, H = height, Le =

length, W = width.

Family Fasciculithaceae Hay and Mohler, 1967

Genus Fasciculithus Bramlette and Sullivan, 1961

Fasciculithus involutus Bramlette and Sullivan, 1961

Plate III, Fig. 10

1961 Fasciculithus involutus Bramlette and Sullivan,

p. 164, Plate 14, Figs. 1–5.

1971 Fasciculithus involutus Bramlette and Sullivan,

1961; Perch-Nielsen, p. 351, Plate 4, Figs. 1–10; Plate

7, Fig. 5; Plate 14, Figs. 28–30.

1989 Fasciculithus involutus; Varol, Plate 12.5, Fig. 5.

Remarks: Medium-sized species of Fasciculithus

(H∼8 μm, W∼8 μm) consisting of a cylindrical

proximal column with several (around ten) conspicuous

surface ridges and many depressions usually arranged in

various cycles and an overlying very low cone.

Fasciculithus janii Perch-Nielsen, 1971

Plate III, Figs. 11–15

1971 Fasciculithus janii Perch-Nielsen, p. 352, Plate

5, Figs. 1–4 (non Plate 14, Figs. 37–39).

1973 Fasciculithus pileatus Bukry, p. 307, Plate 2,

Fig. 1 (non Plate 1, Figs 7–9; Plate 2, Figs 2–5).

1989 Fasciculithus janii Perch-Nielsen, 1971; Varol,

Plate 12.5, Figs. 1–2.

1989 Fasciculithus janii Perch-Nielsen, 1971;

Aubry, p. 132, Figs. 127–131 (non p. 130, Figs. 124–126).

Fasciculithus bitectus Romein, 1979; Aubry, p. 130,

Figs. 122–123 (non Fig. 121).

1989 Fasciculithus pileatus Bukry, 1973; Aubry,

p. 130, Fig. 110 (non Figs. 107–109, 111–114).

2002 Fasciculithus pileatus Bukry, 1973; Steurbaut

and Sztrákos, Plate 4, Fig. 10.

2002Fasciculithus janii Perch-Nielsen, 1971; Steurbaut

and Sztrákos, Plate 3, Figs. 10–11 (non Plate 4, Fig. 8).

Remarks: Medium-sized species (H∼7 μm, W

disk∼8 μm, W column∼5 μm) marked by a solid,

proximally tapering proximal column and a distal disk,

consisting of a series of radial elements, which form a

central cone around a small central hole. It shows strong

birefringence in cross-polarized light in side view,

marked by a bended cap with a central diamond-like

structure, clearly overlapping the proximal column. The

differences in outline of some specimens (less tapering

and more rectangular, see Plate III, Figs. 11 and 13) are

considered to represent intraspecific variability. Some of

the paratypes, notably these figured with the light mi-

croscope Perch-Nielsen, 1971, Plate 14, Figs. 37–39),

do not belong to F. janii, but to Fasciculithus vertebra-

toides n. sp. (see below) on the basis of differences in

birefringence (irregular pattern with higher order colors

e.g. deep blue), an egg-timer-shaped outline and the

absence of a distal disk. Between crossed nicols the distal

disk inF. janii appears as a single optically uniform cycle of

elements, contrarily toF. bitectus (see Perch-Nielsen, 1985,

p. 482, Fig. 38.24), which shows distally two super-

imposed, optically differently oriented rings of elements.

Fasciculithus magnicordis Romein, 1979

Plate II, Fig. 13

1979 Fasciculithus magnicordis Romein, p. 149,

Plate 9, Figs. 12–13.

Remarks: Medium-sized species (H∼ 7 μm,

W∼9 μm) with flat cylindrical outline, consisting of

20 to 30 wedges with a smooth outer surface and a large

and deep distal depression (central body).

Fasciculithus magnus Bukry and Percival, 1971

Plate II, Figs. 7–12

1971 Fasciculithus magnus Bukry and Percival, p. 131,




1979 Fasciculithus magnus Bukry and Percival;

Romein, p. 148, Plate 9, Fig. 14.

1985 Fasciculithus magnus Bukry and Percival,

1971; Perch-Nielsen, p. 483, Figs. 38.64, 39.6–7.

1989 Fasciculithus magnus Bukry and Percival,

1971; Aubry, p. 110, Figs. 1–4; p. 112, Fig. 5–8.

Remarks: Easily recognizable large species

(H∼12 μm, W prox∼9.5 μm, W dist∼12 μm) marked

by a solid column, consisting of a short proximal part

and a much higher distal part. The latter shows a deep

conical depression.

Fasciculithus pileatus Bukry, 1973

Plate III, Figs. 23–26

1973 Fasciculithus pileatus Bukry, p. 307, Plate 1,

Figs. 7–9; Plate 2, Figs. 2–5 (non Plate 2, Fig. 1).

1989 Fasciculithus pileatus Bukry, 1973; Varol,


Remarks: Medium-sized species (H∼6 to 8 μm,W∼6

to 8μm)with truncated cone-shaped column, covered by a

lens-shaped cap, which does not extend beyond the

column. In cross-polarized light, the bisected column and

the cap form three distinct bright areas in side view.

Fasciculithus tympaniformis Hay and Mohler in Hay

et al., 1967

Plate II, Fig. 25


et al., p. 447, Plate 8–9, Figs. 1–5.

1967 Fasciculithus tympaniformis Hay and Mohler

in Hay et al., 1967; Hay and Mohler, p. 1537, Plate 204,

Figs. 10–15; Plate 205, Figs. 4,5,7,8.

1971 Fasciculithus tympaniformis Hay and Mohler,

1967; Perch-Nielsen, p. 349, Plate 1, Figs. 1–5, 7.

1985 Fasciculithus tympaniformis Hay and Mohler in

Hay et al., 1967; Perch-Nielsen, p. 483, Fig. 38.37–38,

Fig. 39.10.

1989 Fasciculithus tympaniformis; Varol, p. 304,


2002 Fasciculithus tympaniformis Hay and Mohler in

Hay et al., 1967; Steurbaut and Sztrákos, Plate 4, Fig. 24.

Remarks: Species of variable size (H∼5.5 to 8 μm,

W∼5 to 7 μm) with a sub-cylindrical distally slightly

tapering column, forming a rounded, slightly pointed

end. The outline is smooth, without conspicuous ridges

and depressions. A few tabular plates are present on the

pointed end. In side view, in cross-polarized light, the

longitudinal optical extinction line is bifurcated or

passes from vertical to oblique at the central body.

Fasciculithus ulii Perch-Nielsen, 1971


1971 Fasciculithus ulii Perch-Nielsen, p. 350, Plate 2,

Figs. 1–4; pl. 14, Figs. 17–18.

1979Fasciculithus ulii Perch-Nielsen; Romein, p. 149,

Plate 4, Fig. 7.

1989 Fasciculithus ulii; Varol, Plate 12.5, Fig. 10.

2002 Fasciculithus ulii Perch-Nielsen, 1971; Steur-

baut and Sztrákos, Plate 4, Fig. 11–13.

Remarks: Medium-sized (H∼7 μm,W∼7 μm) robust

form with an irregularly outlined column, marked by

various conspicuous protruding elements. The proximally

tapering column is covered by a distal dome-like

structure, consisting of one or more flat cycles of

elements.

Fasciculithus varolii n. sp.


Derivation of name: In honour of Dr. Osman Varol

(Llandudno, UK), author of a high-resolution low to

middle latitude Paleocene calcareous nannofossil

zonation.

Diagnosis: Small form (∼5.5 μm), of equal height and

width, consisting of three distinct structures, including a

proximal column, a middle cycle of lateral elements and a

distal superimposed mushroom-shaped cone.

Description: The proximal column is only half as

high as the fasciculith. It is highly concave at its

proximal end and made up of numerous elements with

clear edges. It is covered by a distal dome-shaped

structure, consisting of a rather small cycle of lateral

elements, which slightly overlap the column. A much

higher, but slightly less wide mushroom-shaped cone

occurs on top of this cycle. Both the lateral cycle and the

dome are well distinguishable as two superimposed,

optically different structures in cross-polarized light in

side view.

Dimensions: Height 5.2–6.4 μm, width 5.3–6.2 μm.

Holotype: Plate II, Fig. 18 (IRScNB b4984).

Paratype: Plate II, Fig. 17 (IRScNB b4983).

Type-level: Upper part of Lasseube Formation,

sample L10, Uppermost Danian, upper part of nanno-

zone NP4.

Type locality: Loubieng quarry, S Aquitaine, SW

France.

Stratigraphical range: Lower upper part of Laseube

Formation (L10 to L12).

Fasciculithus vertebratoides n. sp.

Plate III, Figs. 1–5, Fig. 21

1971 Fasciculithus janii Perch-Nielsen, Plate 14,

Figs. 37–39 (non Plate 5, Figs. 1–4).

Derivation of name: Vertebratoides = vertebra-like,

points to its superficial resemblance to fish vertebrae.



Diagnosis: Egg-timer-shaped fasciculith with vari-

able size (W∼6 to 8 μm), consisting of a high proximal

column and a low and small distal cone forming a

cylindrical ring of elements.

Description: Fasciculith with an egg-timer-shaped

outline in side view, resembling fish vertebrae. Early

forms (L12: H∼ 5.6 μm, W base∼ 5.6 μm, W

center∼4.5 μm) are much smaller than later forms

(L27: H∼7.2 μm, W base∼8 μm, W center∼5.6 μm).

The proximal column is build up of a series of

conspicuous surface ridges and deep grooves and is

strongly birefringent presenting an irregular color

pattern. A low distal cone is present. It consists of a

cylindrical ring of elements, the width of which is only 1/

3 of the total width of the fasciculith. In single polarized

light this ring is seen as two low knobby protrusions.

Dimensions: Height 5.6–7.2 μm, width base 5.6–

8.0 μm.

Holotype: Plate III, Fig. 5 (IRScNB b4996).

Paratypes: Plate III, Figs. 1–4, Fig. 21 (IRScNB

b4992–b4995).

Type-level: Lower part of Pont-Labau Formation,

sample L31, Top Danian, top of nannozone NP4.

Type locality: Loubieng quarry, S Aquitaine, SW

France.

Stratigraphical range: Upper part of Lasseube For-

mation to base Pont-Labau Formation; from L12 to L32.

Remarks: Is easily distinguishable from the holotype

of F. janii (Perch-Nielsen, 1971, Plate 5, Fig. 1) by its

egg-timer-shaped form, the absence of a distal cap and

differences in birefringence (see above).

Fasciculithus sp.

Plate II, Fig. 22

Remarks: Relatively small forms (H∼6.4 μm,

W∼5.6 μm) with a proximally tapering column,

consisting of a series of rather smooth elements with

small depressions, especially in the more distal parts, and

a dome-shaped very small cone. In side view, in cross-

polarized light, the longitudinal optical extinction line is

bifurcated. On the basis of these characters these forms

are grouped in a separate taxon, which shares features

with F. involutus (optical colour pattern between crossed

nicols; presence of depressions). However, differences,

such as their smaller size, tapering outline and config-

uration of the cone, exclude inclusion in F. involutus, and

may point to a species new to science.

Family Heliolithaceae Hay and Mohler, 1967

Genus Bomolithus Roth, 1973

Bomolithus elegans Roth, 1973

Plate III, Fig. 17

1973 Bomolithus elegans Roth, p. 734, Plate 15,

Figs. 1–6.

2002 Bomolithus elegans Roth, 1973; Steurbaut and

Sztrákos, Plate 4, Fig. 27.

Remarks: Medium-sized form (D∼8 μm) consisting

of a rather high column and two wider cycles of

elements of almost equal diameter (median and distal

cycle). Only the column is birefringent in cross-

polarised light.

Family Prinsiaceae Hay and Mohler, 1967

Genus Toweius Hay and Mohler, 1967

Toweius tovae Perch-Nielsen, 1971

Plate III, Fig. 16

1971 Toweius tovae Perch-Nielsen, p. 359, Plate 13,

Figs. 1–3, 5, Plate 14, Figs. 8–9.

1995 Toweius eminens (Bramlette and Sullivan,

1961) Gartner, 1971 var. tovae Perch-Nielsen, 1971;

Bybell and Self-Trail, p. 33, pl. 26, Figs. 2, 5a,b, 7, 9;

pl. 27, Figs. 2, 3, 5, 8; pl. 37, Fig. 22.

1998 Toweius tovae Perch-Nielsen, 1971; Steurbaut,


Remarks: Round elliptical coccolith (L∼8.0 μm,

B∼7.2 μm) with irregularly distributed perforations in

the central area. Number and size of perforations vary

greatly, although the small and somewhat larger pores

always co-occur.

Toweius sp.1

Plate II, Fig. 23

Remarks: round rather large elliptical coccolith

(L∼8.8 μm, B∼7.5 μm) with 10 to 15 very small

perforations in the central area of the coccolith.

Toweius sp. 2

Plate II, Fig. 24; Plate III, Fig. 9

Remarks: large elongated coccolith (L∼9.6 μm,

B∼7.2 μm) with around 10 medium-sized perforations.

Central part is strongly birefringent.

Toweius sp. 3

Remarks: small, elongated elliptical coccolith

(L∼4.8 μm, B∼3.9 μm) with 4 to 5 equally sized

perforations in the center.

Appendix B. Alphabetic list of foraminiferal and

nannofossil species mentioned

Planktonic foraminifera

Acarinina strabocella (Loeblich and Tappan, 1957)

(Plate I, Figs. 1–2)



Chiloguembelina midwayensis (Cushman, 1940)

Chiloguembelina sp.

Globanomalina compressa (Plummer, 1927) (Plate I,

Fig. 9)

Globanomalina ehrenbergi (Bolli, 1957) (Plate I,

Fig. 10)

Igorina albeari (Cushman and Bermudez, 1949)

(Plate I, Figs. 8, 11)

Igorina pusilla (Bolli, 1957) (Plate I, Figs. 13–14)

Morozovella angulata (White, 1928) (Plate I, Fig. 4)

Morozovella apanthesma (Loeblich and Tappan,

1957) (Plate I, Fig. 7)

Morozovella conicotruncata (Subbotina, 1947)

(Plate I, Fig. 5)

Morozovella praeangulata (Blow, 1979) (Plate I, Fig. 3)

Morozovella velascoensis (Cushman, 1925) (Plate I,

Fig. 6)

Parasubbotina pseudobulloides (Plummer, 1927)

Parasubbotina varianta (Subbotina, 1953) (Plate I,

Fig. 12)

Praemurica inconstans (Subbotina, 1953)

Praemurica uncinata (Bolli, 1957)

Subbotina triangularis (White, 1928)

Subbotina triloculinoides (Plummer, 1927)

Subbotina velascoensis (Cushman, 1925) (Plate I,

Fig. 15)

Subbotina sp.

Species discussed in text although not recorded:

Globanomalina pseudomenardii (Bolli, 1957)

Benthic foraminifera

Angulogavelinella avnimelechi (Reiss, 1952)

Cibicidoides alleni (Plummer, 1927)

Gavelinella abudurbensis (Nakkady, 1950)

Gyroidinoides globosa (von Hagenow, 1842)

Gyroidinoides subangulata (Plummer, 1927)

Neoeponides duwi (Nakkady, 1950)

Nuttallides truempyi (Nuttall, 1930)

Osangularia velascoensis (Cushman, 1925)

Svenia bulbosa (Halkyard, 1919)

Stensioeina beccariiformis (White, 1928)

Textularia plummerae Lalicker, 1935

Thalmannita madrugaensis (Cushman and Bermudez,

1947)

Tritaxilina cubensis (Cushman and Bermudez, 1937)

Calcareous nannofossils

Bomolithus elegans Roth, 1973 (Plate III, Fig. 17)

Braarudosphaera alta Romein, 1979

Braarudosphaera bigelowii (Gran and Braarud,

1935) Deflandre, 1947; (Plate II, Figs. 14–15)

Braarudosphaera discula Bramlette and Riedel, 1954

Chiasmolithus edentulus van Heck and Prins, 1987

(Plate II, Fig. 21)

Coccolithus pelagicus (Wallich, 1877) Schiller, 1930

Coccolithus subpertusus (Hay and Mohler, 1967)

van Heck and Prins, 1987 (Plate III, Fig. 18)

Cruciplacolithus spp.

Ellipsolithus bollii Perch-Nielsen, 1977 (Plate III,

Figs. 7–8)

Ellipsolithus distichus (Bramlette and Sullivan,

1961) Sullivan, 1964 (Plate III, Fig. 19)

Ellipsolithus macellus (Bramlette and Sullivan,

1961) Sullivan, 1964 (Plate II, Figs. 4, 16)

Fasciculithus billii Perch-Nielsen, 1971

Fasciculithus chowii Varol, 1989

Fasciculithus involutus Bramlette and Sullivan, 1961

(Plate III, Fig. 10)

Fasciculithus janii Perch-Nielsen, 1971 (Plate III,

Figs. 11–15)

Fasciculithus magnicordis Romein, 1979 (Plate II,

Fig. 13)

Fasciculithus magnus Bukry and Percival, 1971

(Plate II, Figs. 7–12)

Fasciculithus pileatus Bukry, 1973 (Plate III,

Figs. 23–26)


et al., 1967 (Plate II, Fig. 25)

Fasciculithus ulii Perch-Nielsen, 1971 (Plate II, Figs.

19–20)

Fasciculithus varolii n. sp. (Plate II, Figs. 17–18)

Fasciculithus vertebratoides n. sp. (Plate III, Figs. 1–5,

Fig. 21)

Fasciculithus sp. (Pl. 2, Fig. 22)

Micrantholithus spp.

Neochiastozygus eosaepes Perch-Nielsen, 1981

Neochiastozygus imbriei Haq and Lohmann, 1976

(Plate II, Figs. 1–3)

Neochiastozygus perfectus Perch-Nielsen, 1971

(Plate III, Fig. 6)

Placozygus sp.

Scapholithus apertusHay and Mohler, 1967 (Plate III,

Fig. 20)

Sphenolithus primus Perch-Nielsen, 1971 (Plate II,

Figs. 5–6; Plate III, Fig. 22)

Sullivania aff. consueta (Bramlette and Sullivan,

1961) Varol, 1992

Sullivania spp.

Toweius pertusus (Sullivan, 1965) Romein, 1979

Toweius tovae Perch-Nielsen, 1971 (Plate III,

Fig. 16)



Toweius sp. 1 (Plate II, Fig. 23)

Toweius sp. 2 (Plate II, Fig. 24; Plate III, Fig. 9)

Toweius sp. 3

Species discussed in text although not recorded:

Toweius eminens (Bramlette and Sullivan, 1961)

Perch-Nielsen, 1971

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